Cash in your silicon chips – paper and plastic are about to make a comeback. As sensors fill the world with an endless stream of data on every aspect of our lives, Moore’s Law dictates that traditional silicon-based systems won’t keep up with demand.
A worldwide race is on to master the production of flexible, biodegradable, low-cost alternatives, giving rise to the Internet of Disposable Things.
YOU’VE HEARD OF the Internet of Things (IoT), where a sensor is put into every tool, device, computer or machine from a mobile right up to a factory? Billions of readings from millions of microchips report on the performance of computers, planes, server farms, fridges, energy plants, lamps and everything in between. According to market intelligence firm IHS Markit, the number of IoT devices will balloon to over 125 billion by 2030.
The last boundary of data collection is from non-silicon-based systems like clothes, food, the environment or even our own bodies. Welcome to the Internet of Disposable Things (IoDT), where temporary or ultra-cheap sensors are embedded or affixed to any number of inexpensive media that aren’t computer-based.
Pretty much everything in the world has a container or wrapper around it (even we do, in the form of garments) – and now the technology to manufacture and embed low-powered, single-use sensors into disposable materials means you can be your very own Internet of Things.
While you might think current IoT is pretty varied (sensors recording the temperature in a house for your smart home app, movement in an electric toothbrush to make sure the kids are brushing properly, or the wear on your brake pads so you know when to replace them), they’re all essentially based on electronics.
The IoDT is based on anything and everything else as long as it meets one single criteria – it’s produced cheaply enough to be discarded, which makes substrates like paper, plastic or fabric its ideal home.
WHILE IOT DEVICES RELY on a microchip, transmitter and a battery to keep them going, the inexpensive IoDT device can’t afford all (in some cases any) of those elements as we know them. Nevertheless, the building blocks will be the same: sensors, telemetry to record and transmit readings, and a power source.
Where IoT inputs are digital data, those of the IoDT could be almost anything – changes to the ambient light, temperature, pressure, mass, acceleration, humidity, chemical make-up, force and more.
One of the critical advances ushering in the disposable sensor world is microelectromechanical systems, or MEMS. Most MEMS sensors are made on silicon wafers, just like computer chips, but use tiny mechanical structures that respond to some physical stimulus like pressure, movement, light, temperature and more. Only a few millimetres in size, they can express readings as electrical signals and – when attached to an equally tiny radio antenna – send data to a nearby receiver.
Silicon electronic sensors cost between 10 and 50 US cents and are suitable for use in consumer products worth $100 and up, such as phones and fitness trackers.
Alissa Fitzgerald, founder of MEMS manufacturer AM Fitzgerald, estimates that disposable sensors will need to be made for less than one cent if they’re used for items costing around $10 in the medical, food, fitness, package tracking or garment fields. That means the market rate for silicon would need to be about a fifth of what it is today (fat chance).
In 2017, Belgian researchers built a printed plastic near-field communication (NFC) chip out of indium, gallium, zinc and oxygen. Essential for contactless payment systems and other proximity- based technologies, the researchers aim to make their chips refined enough for high-volume manufacturing that they can be produced to the tune of around 1¢ per square centimetre.
As similar research to manufacture IoDT devices using inexpensive materials continues, it will further drive the price down and make sensors available for ever cheaper uses (and using safer, more benign materials) – from T-shirts and bananas to skin and body parts.
Getting the data is half the job; reporting it to a computer or app that can make sense of it is the other. Your ubiquitous mobile or tablet is an obvious candidate to receive and synthesise all the new IoDT data, but mobile phones understand GSM, UMTS and LTE cellular signals, Wi-Fi, Bluetooth and a handful of others.
What if your telemetry is a simple electrical charge, a chemical reaction, a shift in air pressure or a subtle temperature variation? Of course, we have tools that can speak all those languages – a voltmeter, blood sugar monitor, barometer and thermometer respectively – but they’re not found in the average smartphone (yet).
Until they are, designers have to resort to new tools to listen in. One of the most popular is the passive coil, which transmits by induction rather than by active signalling. It sounds like double Dutch, but in fact you’ve already used it – it’s the basis for radio frequency ID (RFID) and NFC systems we’ve had for many years in retail anti-theft, self-checkout and tap- to-pay.
Putting a $1 battery on a supermarket shrink wrap that costs less than a cent won’t just drive the price of goods and handling unfeasibly high, it’ll be an environmental nightmare.
In the absence of power sources that cost a fraction of packaging, clothes or medical devices (think of blood glucose test strips), we need to look elsewhere – and the most likely solution at the moment seems to be passive power.
Just as an RFID tag only comes to life when it’s in the presence of a reader, many IoDT devices need to extract power from their environment to work when they’re called for and not before. And there’s no lack of sources, from the movement of blood in a vein to the release of gas from food, orientation to gravity and everything in between.
Since the natural home of many disposable sensors will be the human body, it makes perfect sense to use our heat, movement and chemistry inside – and out – to power them. Blood pulsing past a sensor could act like a waterfall over a turbine, and the movement of air in and out of our lungs would nicely replicate the operations of a mini wind farm.
A recent device developed by scientists at France’s National Centre for Scientific Research and the University of California, San Diego, is worn on the skin. It flexes and stretches as the wearer moves, producing electrical energy by oxidising the lactate in sweat. At the moment it produces only enough power for a single LED light, but work is being done to amplify the voltage to power larger devices.
Then there’s 4D printing – think 3D printing, but where the printed matter reacts further upon contact with certain conditions. 3D printed cells, for example, can start to divide, fold and interact when they come into contact with other cells or in the body. A microscopic chemical turbine could fire up when it reaches body temperature, and as any physicist will tell you, movement equals energy.
When biomedicine does move beyond lithium or cell batteries it will open the field exponentially. A group at the University of Pennsylvania has developed an electrochemical battery made of paper where polymers are incorporated in a network of cellulose fibres, performing the oxygen-blocking and proton- exchange properties of organic decomposition.
And in June this year, Seokheun Choi, Associate Professor of Electrical and Computer Engineering at Binghamton University, New York, led his team to develop a biobattery made from organic microbial fuel cells where bacteria in the device is used to disintegrate the device itself at the end its useful life.
“One of the critical challenges to make the Internet of Disposable Things is a power source,” says Choi. “It has to be disposable, eco-friendly and inexpensive.”
To that end, his research group embarked down two pathways – disposable paper-based batteries and long-term microbial fuel cells – then found themselves meeting in the middle.
“The biobattery was a combined technique of those two,” says Choi.
“We enhanced the power duration by using solid- state compartments – but the device is still a form of a battery without complicated energy-intensive fluidic feeding systems that typical microbial fuel cells need.”
Getting down to business
THERE’S A NASCENT COMMERCIAL field sprouting up around the IoDT, including AM Fitzgerald, which has specialised in MEMS since 2003. Most of its market so far has been high-performance silicon sensors in implantable medical devices, scientific instruments, aircraft, spacecraft – things Alissa Fitzgerald says you can’t find just anywhere.
But she told me on the phone from her office south of San Francisco that she’s recently seen a change. “About five or six years ago I started to see this trend where more of the university research was in developing sensors on flexible – or even just cheaper – substrates like paper or fabric.”
Today, thanks to the work done in labs and universities, a lot of the theory and many aspects of the practice are in place. The only bottleneck remaining is the manufacturing infrastructure.
“Companies that make printing presses, and textile manufacturers which already have equipment, will probably be best positioned to take this on,” says Fitzgerald. “If you want to buy a shirt that already has sensors embedded in it, where’s that going to be done? It’s going to be at a textile company.”
Such businesses have the large-scale means to merge electronics manufacturing with that of making paper, fabric or other flexible materials by producing it on huge rolls – a merger that hasn’t occurred at the industrial level yet.
Notable by its absence in Fitzgerald’s imagined future is the semiconductor industry.
Household names in the industry – such as Intel and AMD – have designed and built almost every other electronic sensor in your home and workplace today thanks to their command of the computer and smartphone markets.
“A semiconductor factory is essentially a giant clean room,” Fitzgerald says, referring to the high threshold for process fidelity and the purity of the parts and processes needed. These are markers not required at a factory making exercise books or $5 shirts.
Then there’s the precedent of “fabless” (as in, fabrication-free) chip-making. Small semiconductor companies in the 1980s drove an explosion of innovation by designing inhouse but outsourcing actual fabrication to established third-party foundries and manufacturers, thus avoiding the huge capital outlays and risk that come with equipment, plants and staffing.
Today it’s the natural home of some of the biggest names in the information and communications technology (ICT) industry. Among the top five companies by sales, using fabless manufacturing in 2017 were superconductor giant Qualcomm, graphics and gaming specialists nVidia and, of course, Apple.
In fact, some work in hybridising manufacture has already been done – and from a surprising quarter. University of Illinois chemical and biomolecular engineering professor Ying Diao was working with a molecule that was studied as a cancer treatment by inserting itself into DNA to prevent replication.
After it failed in the test phase as an effective cancer treatment, Diao – who happened to be working in the disparate fields of pharmaceutical engineering and printable electronics – noticed that “their molecular structures looked much like the organic semiconductors we were working with in the rest of my group… This convergence of my two research areas was totally unexpected”.
Composed of stacked columns of electrically conductive rings connected with hydrogen, the molecules can pass charges across the columns, forming a bridge that behaves like a semiconductor. They interact with biological material using very specific markers and measures, which makes them ideal biosensors. Better yet, they can be produced from a printer, so they’re able to be affixed to flexible substrates.
IN TODAY’S DATA-DRIVEN WORLD, is it possible to make too much information? In 2017, IT platform provider Domo.com released research that estimated we collectively produced 2.5 quintillion bytes of data every day That’s 2,500,000,000,000,000,000 bytes – or two-and-a-half million terabytes.
Late in 2019, market intelligence provider IDC said IoT data would continue to balloon, reaching 79.4 zettabytes (79,400,000,000,000,000,000,000 bytes), a jump of over 31,000 times.
Now imagine what happens if we factor in communications between every sock, jogging shoe, bucket of fried chicken, bottle of soft drink and headache pill. “Big” won’t come close to doing justice to such a deluge.
The possibilities for learning are just as vast. As data scientist and machine learning engineer Luciano Strika points out, studies like whether apples make you live longer, or a vegan diet protects against heart attack, are based on “30 to 150 people – usually young white male university students”.
“Imagine conducting those same studies with a population of a thousand or a million,” he says. “And it’s a more random set with people of many ethnicities, age groups, etc. Suddenly you’ll find more granular results – maybe apples plus oranges plus being female helps prevent a certain type of heart disease.”
Strika also thinks it will prompt a new breed of intelligence. “What may really amaze us is emergent behaviour – if we’re tracking heart rates, deliveries and food quality, the interaction between these data points might provide us with very interesting results.”
In fact, the IoDT might comprise such a surge in data collection, transmission and storage that it entirely changes the way the world computes. Rohit Dewani, an engineer with Mumbai-based industrial IoT systems provider CraneSCADA, says that to analyse and generate value out of such volume will require a paradigm shift.
“[It] will require a complete overhaul of our servers, hard discs and deep learning capabilities,” he says. “Current generation [hardware] will need to be drastically optimised due to the amount of data, and algorithms will need to become even more robust.”
But with bigger data will come bigger privacy concerns, says Monica Eaton-Cardone, founder and COO of US financial services company Chargebacks911. “Interestingly, it could very well be that our fear of data breaches triggers a demand for disposable IoT devices,” she says.
“Something that only temporarily tracks your personal data might be perceived as less risky than a device used over many years.”
Paris-based author and strategist Rahaf Harfoush, who honed her expertise about technology and innovation at the World Economic Forum, thinks the biggest question of the IoDT age will be data sovereignty and our rights when so much more about us is being recorded and transmitted.
“We’re shifting from an age of data abundance to integrative data,” she says. “It’s the difference between someone Googling about weight-loss tips and being targeted by advertisers versus their smart fridge sharing information about their weight and the food they buy via obscure and overly-legal agreements. It becomes even more true as datasets are integrated with each other to form more complex and accurate profiles of us.”
But while there are certainly data storage and security concerns that need to be addressed if this is all going to enjoy mass economic and consumer adoption, the benefits will far outweigh the risks.
By applying other methodologies like machine learning to the flood of information the world around us will generate, it’s possible that we’ll be able to connect dots we never knew existed to further improve society.
Not only will trains, planes and factory equipment work for us better, the Internet of Disposable Things will see to it that food, medicine and product packaging do so too.
A few Tuesdays from now, you get out of bed early and blearily pull on your clothes for your morning exercise. You head for the kitchen to grab a snack. In the fruit bowl, each item’s Forever Fresh sticker registers its ripeness and nutritional value, and you take the fruit with the highest content.
As you pop your Respiratory Calorimeter Pellet (RCP) into your mouth and head out the door to jog down the street, your T-shirt’s SmartHeart loads up, logging information about your heart rate.
When you start to push up the neighbourhood hill about a kilometre in, your phone changes the music to slow your rate. You make it to the top without getting last week’s warning to stop for a break and victoriously run the rest of the route with music that matches the tempo of your improving heart rate.
Back at home, the RCP (which measured the chemical content of your inhaled and exhaled breaths) shows that the run burned 2,035kJ – not bad for an hour round the neighbourhood. You shower, stick your Sodi-Kit strip to your calf, and head out into the day.
It’s been so busy through the first part of the work day that you’ve forgotten lunch, until your phone vibrates with a notification from the Sodi-Kit strip’s data, which is showing that your blood sugar and sodium are low enough to be a drag.
While you’re eating lunch, you get a call from your GP’s office asking you to make an appointment to come in soon. You’re on blood-thinning medication following a recent heart arrhythmia event, and the SmartCaps pill that you took this morning has alerted your doctor that your metabolism is absorbing the drug faster than expected.
It’s bedtime. You’ve elected to spend your last minutes of consciousness old-school, catching up on the day’s events through news sites on your phone. And then – darn.
The report bings in on your day’s stats: an analysed combination of RCP, SmartHeart, SmartCaps, Sodi-Kit and several others.
The recommendations for tomorrow include an extra 10 minutes of exercise, a fair bit less coffee and a delectable array of legumes for dinner. Plus a reminder to confirm your appointment with the doc about the warfarin.
Sensing both trouble and the need to head it off at the pass, your phone automatically offers your favourite musical soporific: an endless loop of the humming bit from “Don’t Worry Be Happy”.
Respiratory Calorimeter Pellet
Measuring calories burned during exercise is usually a matter of averages. Take your weight, age, sex, etc and multiply according to the duration and intensity of exercise – also called “indirect calorimetry”. But since the mid ’60s there’s been a way of measuring the chemical content of inhaled and exhaled breaths. There’s a lot of arcane chemistry involved, and a 2017 study found the technique “not sufficiently accurate” to compete with indirect calorimetry, but technology has shown us nothing if not a tendency to overcome such hurdles.
A more traditional IoT sensor, your phone’s GPS knows where you are and can plan your most efficient workout according to the path ahead. Say there’s a long, straight stretch coming up. Because your Pathfindr app has access to both the local geography and the SmartHeart app tracking your fitness regimen, it suggests a sprint, knowing that the best time for a harder rep.
Your SmartHeart’s sensor is based on technology that already exists. A stent placed inside the heart contains a membrane of quartz with an antenna inside, forming
a capacitor. When blood pressure squeezes down on the membrane it changes
the capacitance and therefore the resonant frequency of the circuit. An external reader embedded in your shirt interrogates the antenna with an RF signal of known frequency, then compares it with the altered frequency of the return signal.
FISC (Fidelity In Supply Chain)
Is that single vineyard olive oil really sourced from the Italian hill town it claims? The inexpensive FISC tag or sensor attached to the bottle (or pair of shoes, or expensive fountain pen, etc) contains and transmits information about the entire trip from grove to supermarket shelf to prove product authenticity.
Eat a banana too early and it can affect your ability to digest complex carbs, too late and it contains fewer nutrients and more sugar. Work at New York’s Clarkson University has created a paper sensor that can detect food spoilage from the supermarket packaging or even the skin of the fruit itself. Embedded nanostructures change colour (like litmus paper or a home pregnancy test) in response to the gases released by decomposition, so a visual sensor could read the colours and report the result digitally. A lab at Harvard University is also adapting a paper-based diagnostic test strip sensor to transmit data by radio.
If you know any diabetics, you’re familiar with the disposable strips that read
the glucose in a blood sample. Blood deposited on the strip prompts a chemical reaction which sends a specific electrical current to the meter depending on the mix. The salt (sodium) content of blood is also important – particularly in relation to fitness – so similar technology could be embedded into a small strip of tape and applied to your skin, albeit with a smaller, less permanent reader than an everyday glucose monitor. Biodegradable electrochemical sensors already exist that use the salt content in the body to provide power through electrolytes, so your Sodi-Kit can read your salt content and draw power from it at the same time.
Your prescription drugs could be delivered in a pill that – after your stomach acids have broken it doewn and left only the microscopic magnesium and cooper sensor – react with it to activate it chemically. Signals about the volume and efficacy of the drug in your system are sent to the band-aid-like patch on your skin that collects the readings, sending them to your phone for you or your dictor. Ingestible sensors have been commercially available for at least five years.